1. Field of the Invention
The present invention relates to novel retinoids, as coumarin retinoids and/or purine retinoids, and compositions thereof, which exhibit therapeutic and/or biological activity on cancer or precancer cells, as well as to methods of using same.
2. Description of the Related Background Art
Retinoids play an important role in the development and differentiation of epidermal cells, as well as in reversing precancerous lesions. Clinical trials have been conducted using N-(4-carboxyphenyl) retinamide in the treatment of some precancerous lesions, oral leukoplakia, vulval leukoplakia, atypical dysplasia of the cervix and the gastric mucosa, and the like (Han et al., in vivo 4:153-160 (1990)). Other retinoids, such as isoretinoin and etretinate, are in current use as prescription drugs for the treatment of acne and psoriasis (Gander et al., U.S. Pat. No. 4,126,693).
However, retinoids have a significant level of toxicity, and treatment using known retinoid agents suffers from problems due to the level of toxicity and side effects which accompany administration of known retinoid compounds. Accordingly, there exists a need to provide novel compounds having retinoid activity but which have less toxicity and/or side effects.
Smith et al., J. Clin. Oncol. 10 (5):839-864 (1992), reviews the use of retinoids in cancer therapy with most of the emphasis on anti-tumor effects in patients with acute promyelocytic leukemia (APL). Smith et al. reports that the natural retinoid, all-trans-retinoic acid (RA), ##STR2## induces cell differentiation in some human acute myeloid leukemia (AML), neuroblastoma, teratocarcinoma, melanoma, and rat rhabdomyosarcoma cells and also appears to play an essential role in the normal differentiation of epithelial cells. Clinical toxicities associated with the use of RA in dermatologic studies are listed in Table 6 of the Smith et al. reference with disclosure in the text that retinoids are recognized as powerful teratogens.
Kizaki et al., Seminars in Oncology 19 (1):95-105 (1992), reports that retinoids are potent anti-carcinogenic agents in many experimental models and that they inhibit growth and induce differentiation of transformed neoplastic cells. A number of references specifically relate to retinoic acid derivatives as anti-cancer agents. Just et al., U.S. Pat. No. 4,385,175, discloses esters of retinoic acid with azetidinones useful as anti-cancer agents. Philippe et al., U.S. Pat. No. 5,096,713, discloses retinoic esters of L-cladinose which exhibit anti-tumor activity. The Paust Canadian Patent No. 1,127,170, is specifically directed to retinic acid N-(carboxy)-phenylamindes and 7,8-dehydro-retinic acid N-(carboxy)-phenylamides, and discloses that, while the retinic compounds are predominantly directed toward preventing cancer, they may be used for therapeutic treatment of tumors of the bladder, the mammary gland, the skin and the mucous membranes.
A number of references disclose retinoids being used in cancer prophylaxis and as inducers of cell differentiation. For instance, Newton et al., Cancer Res. 40:3413-3425 (1980) discloses a long list of esters, amines and amides of retinoic acid and their activity in cancer prophylaxis. None of the listed compounds are related to flavonoids or chalcone retinoids. Du et al., Inst. Mater. Med. Chinese Acad. Med. .Sci. Beijing 17:331-337 (1982), discloses the retinamides R.sub.II (N-4(hydroxycarbophenyl)retinamide) and R.sub.I (4-(ethoxycarbylphenyl)-retinamide) and their utility as cancer preventatives. Song et al., Inst. Mater. Med. Chinese Acad. Med. Sci. Beijing 19:576-581 (1984), also relates to the property of the retinamides R.sub.I and R.sub.II as cell differentiation inducers. The Shealy patent, U.S. Pat. No. 5,124,083, discloses derivatives of retinoic acid as cell differentiation agents for cancer prevention and treatment and the Shealy et al. publication, J. Med. Chem. 31:1124-1130 (1988), discloses the chemopreventative activity of bifunctional retinoic acid esters. Dawson, J. Med. Chem. 27:1516-1531 (1984), Dawson et al., J. Med. Chem. 24:583-592 (1981), Kagechika et al., J. Med. Chem. 32:1098-1108 (1989), Skrede et al., Eur. J. Clin. Investig. 21:574-579 (1991) and Loev et al., U.S. Pat. No. 4,523,042, all disclose various retinoid compounds which are cell differentiation agents. Gander, U.S. Pat. No. 4,323,581, discloses the use of N-(4-hydroxyphenyl)-all-trans-retinamide for treatment of breast cancer while in U.S. Pat. No. 4,310,546, Gander discloses the use of N-(4-acyloxyphenyl)-all-trans-retinamide in the prevention of epithelial cancer. The Gander et al. patents, U.S. Pat. Nos. 4,126,693 and 4,190,594, relate to other properties of esters and amides of retinoic acids.
Furthermore, Blazsek et al., Biomed. Pharmacother. 45:169-177 (1991), Degos, Biomed. Pharmacother. 46:201-209 (1992), Castaigne et al., Blood 76 (9):1704-1709 (1990), Chomienne et al., Blood 76 (9):1710-1717 (1990), and Lo Coco et al., Blood 77 (8):1657-1659 (1991) all disclose using retinoic acid in differentiation therapy for patients with acute promyelocytic leukemia (APL).
Some flavonoids and chalcones have been found to have anti-tumor properties. Middleton et al., Biochem. Pharmacol. 43:1167-1179 (1992), relates to the anti-tumor effects of flavonoids, and Harvey et al., J. Org. Chem. 53:3936-3943 (1988) and J. Org. Chem. 55:6161-6166 (1990), and Nair et al., Carcinogenesis 12 (1):65-69 (1991) relate to anti-carcinogenic coumarin and flavone compounds. Jing et al., Chinese J. Pharmacol. Toxicol. 6 (4):278-280 (1992) discloses that an isoflavone, diadzein, inhibits melanoma cell growth. The Ishizuka et al. patent, U.S. Pat. No. 5,096,924, discloses anti-cancer effects of a substituted 2-benzopyrinone. Ito et al., U.S. Pat. No. 4,960,908, Briet et al., U.S. Pat. Nos. 4,602,034, 4,783,533, and 5,116,954, and Kramer et al., U.S. Pat. No. 4,713,465, all teach 4-benzopyrinone compounds as anti-cancer agents.
Preuss-Ueberschar et al., Drug Res. 34:1305-1313 (1984) discloses that benzopyrones, which include coumarin, are not teratogenic. The pharmacology of coumarin-related compounds is reviewed by Egan et al. which indicates that coumarin-related compounds are known to inhibit the carcinogenicity of carcinogens and that coumarin has been tested for treatment of melanoma.
Edwards et al., J. Med. Chem. 33:1948-1954 (1990) relates to the anti-mitotic action of chalcones. Cassady et al. and Ito et al., Abstract Collection of International Symposium on Recent Advance in Chemistry and Molecular Biology of Cancer Research, Beijing, China, 1991, pp. 5-6 and 68-69, respectively, relate to the anti-mitogenic effects of various flavonoids, including biochanin A.
Han et al., Chinese J. Cancer Res. 2 (3):51-53 (1990), reports the effects of an isoflavone, S86019, which is an active component of a medicinal herb used in China, Pueraria lobata. The structure of S86019 is not disclosed. In a different publication, in vivo 4:153-160 (1990), Han et al. evaluates the R.sub.II retinamide compound as a cancer prevention agent and as a cancer chemotherapeutic agent and discusses the induction of cell differentiation of HL60 cells using a combination treatment of R.sub.II with S86019. The combination of R.sub.II with S86019 acts synergistically in inducing cell differentiation and it is reported that this combination may have clinical applications with minimal patient toxicity.
Citation of any document herein is not intended as an admission that such document is pertinent prior art, or considered material to the patentability of any claim of the present application. Any statement as to content or a date of any document is based on the information available to applicant at the time of filing and does not constitute an admission as to the correctness of such a statement.